Objective: The objective of this study was to establish the profile of major congenital malformations at Nizwa Hospital, which is a major hospital in the Al-Dakhliya region of Oman.
Methods: All births with birthweight more than 500 g were prospectively studied from January 1993 through December 2002 for a period of 10 years. A congenital anomaly register was maintained in the special care baby unit (SCBU) and details of each case were recorded after parents' interviews, clinical evaluation and relevant radiological and laboratory investigations. The major malformations were classified as multiple or single-system abnormalities as well as genetic or non-genetic disorders.
Results: Of the 21 988 births during the study period, 541 babies (24.6 per 1000 births) had major malformations. Of the 541 babies, 158 (29.2%) had multiple malformations and 335 (61.9%) had involvement of a single system. In 48 (8.9%) babies a complete evaluation was not possible. Of the cases with multiple abnormalities, 57 had recognized syndromes, of which 28 (49.1%) were autosomal recessive disorders. Seventy (12.9%) cases had chromosomal abnormalities. The most common systems involved in neonates with single-system malformations were the gastrointestinal system (100 cases), the central nervous system (79 cases) and the cardiovascular system (63 cases). Although the consanguinity rate of 53.1% among Omani births almost matched with the regional average of 52.7%, it was 76% among those with major malformations. Also, there was an increased clustering of multiple abnormalities and rare recessive disorders in cases with closely related parents and grandparents. The birth prevalence of major malformations was 14.6 per 1000 in non-Omani births as compared to 25.2 in Omani births (P < 0.05). Genetic factors could be implicated in 343 (63.4%) cases and 130 (37.9%) of these were potentially preventable.
Conclusion: Genetic disorders account for a significant proportion of congenital malformations in Oman.